Back to BiologyPractice this
Paper 2
Ecology
Both
Food webs show how energy moves through ecosystems.
Key Facts
- Biodiversity is higher in stable, undisturbed ecosystems.
- Human impacts include pollution, deforestation, and climate change.
- Quadrats can be used to estimate population size.
- Indicator species show pollution levels.
Topics Covered
Ecosystems and Food Webs
What you need to know
- •Food chains show energy transfer between trophic levels.
- •Only about 10 percent of energy transfers to the next level.
Exam Tips
- Use arrows to show energy flow, not who eats whom.
Cycles and Resources
What you need to know
- •Carbon and water cycles move materials through ecosystems.
- •Decomposers recycle nutrients back into the soil.
Exam Tips
- Name at least two processes in each cycle.
Sampling and Distribution
What you need to know
- •Quadrats estimate abundance and distribution.
- •Transects show changes across a gradient.
Exam Tips
- Use a random number table to avoid bias.
Decay and Cycling
What you need to know
- •Decay releases carbon dioxide in respiration.
- •Decay is faster in warm, oxygen-rich conditions.
Exam Tips
- Link decay rate to temperature and moisture.
Key Terms
Biodiversity
The variety of different species in a habitat.
Trophic level
Position of an organism in a food chain.
Quadrat
A square frame used to sample organisms in a habitat.
Transect
A line used to sample across a gradient.
Loading practice drills...
Common Exam Questions
Explain one way farming can reduce biodiversity.
3 marksmediumPaper 2
Model Answer
Monoculture removes other plants and habitats, so fewer species can survive.
What examiners want to see
- ✓Link farming practice to habitat loss.
- ✓Mention fewer species.
Describe how you would use quadrats to estimate the number of plants in a field.
4 marksmediumPaper 2
Model Answer
Place quadrats randomly, count plants inside, find the mean, then multiply by the total field area.
What examiners want to see
- ✓Mention random placement.
- ✓Use mean per quadrat.
- ✓Scale up to total area.
Related Topics
Other topics you might find useful